Design, Synthesis And Herbicidal Activity Of Novel PPO Inhibitors Containing Benzothiazole Moeity

As the continuonal development of the modern society, as the destroying of the environment, the human environmental awareness will become increasingly. Nowadays, "efficiency, low toxicity, and environmental friendly" has become the theme of new pesticide discovery. Protoporphyrinogen oxidase inhibitor class of herbicides that satisfy such demands. Protoporphyrinogen oxidase (PPO, E.C.1.3.3.4), the last common enzyme in the tetrapyrrole biosynthetic pathway leading to chlorophyll in plant and heme in animal, has been identified as one of the most significant targets for herbicide discovery. In plants, the protoporphyrinogen oxidase action target is light-dependent herbicides, the herbicides with Substrate com.petitive inhibition results will lead to tissue of blessing and death. So in the agricultural field, PPO inhibitors have been used as herbicides for many years.In this paper, we used the method of combination of active structural moieties, and bioisosterism principles, base on the commercialization PPO inhibitor molecules Saflufenacil and Flumioxazin, designed and synthesized two class of structure pyrimidindiones and indazoles which contant three categories 153 target compounds. Preliminary activity screening showed pyrimidinediones and indazoles two structures having a good activity, and found a number of compounds having a good herbicidal activity in the low dosage at 9.375 g.ai/ha, which are worthy of further optimization to obtain better candidates.We summarized the structure evolution of the PPO-inhibiting herbicides and elucidate the focused area of current research.153 compounds were designed and synthesized by a multiple steps synthetic procedures, they were characterized by 1H NMR, ESI-MS, element quantitative analysis and X-ray analysis.The in vitro PPO inhibition of these newly synthesized compounds were assayed and the further greenhouse herbicidal activity were also investigated. The bioassay results indicate that a number of coumpounds show good PPO inhibition. In comparison several compounds such as pyrimidindones compounds Y11046 (9.0 nM), Y11047 (7.3 nM), Y11050 (7.2 nM), Y13021 (8.0 nM) and indazoles compounds Y10124 (0.49 nM)、Y10125 (0.38 nM)、Y10126 (0.40 nM)、Y10127 (0.67 nM) displayed higher PPO inhibition than commercialized PPO-inhibiting herbicides, oxadiazon (0.024 μM) and sulfentrazone (0.027 μM).According to the greenhouse biologogical results, a number of pyrimidindones compounds show good activity in the post-emergence control of Broadleaf weeds and Grass weeds, such as compounds Y11046、Y11047、Y11048、Y11049、Y11050、Y11090、Y11093、Y11101、Y11102 still have good activity in the post-emergence control of Broadleaf weeds and Grass weeds at the dosage 9.375 g.ai/ha. The indazoles compounds shows good activity in the post-emergence control of Broadleaf weeds. At the dosage of 150 g.ai/ha, the compounds Y10124、Y10127、Y11035、Y11036、Y11037 shows moe than 85% post-emergence control of a wide range of Broadleaf. With the dosage as low as 37.5 g.ai/ha, the compounds Y10124、Y10125、Y10127、Y10128、Y11033、Y11035、Y11036、 Y11037 still shows good activity in the post-emergence control of Broadleaf weeds.The preliminary structure-activity relationships of pyrimidindones and indazoles were summarized, which indicate that the pyrimidindones and indazoles scaffold could be identified as a novel herbicidal lead strcture.